1. Field of the Invention
The present invention relates to a device, system and method for monitoring the status of a railcar handbrake, and for providing an alert when the car is in motion while the handbrake is applied.
2. Description of the Related Art
Wheel damage in the railroad industry is responsible for significant maintenance costs. A common cause of wheel damage is moving the railcar while the handbrake is applied. If the handbrake is applied when the railcar is moving, the wheels of that car will not turn. Instead, they will slide on the rail, resulting in damage to the wheels, e.g., slid flats, spalling, shelling, etc. If these conditions are sufficiently bad to cause an individual wheel to be condemned, the wheel set must be replaced. Replacement of wheel sets requires the railcar to be removed from service and is one of the most expensive maintenance items for railcars.
Each railcar typically has a brake rigging on the underside of the railcar that includes an arrangement of rods, levers and chains forming a mechanical linkage connected to brake shoes which can be applied to rub against the train wheels, using friction to slow and stop the train. This brake rigging can be operated by an air cylinder that is part of a centralized train air brake system controlled from a central location, e.g., the locomotive. The air brake system is used to slow and stop entire trains.
Most railroad cars also have manually-operated mechanical hand brake devices that can set and release the brakes. They are used to maintain railcars at rest such as when in the rail yard or at a customer for loading and unloading. Manually operated handbrake devices typically operate at least a portion of the same brake rigging on the railcar used by the air brake system, bypassing the air cylinder to engage the brake shoes.
In one form, the handbrake has a manually operable hand wheel located on the B end of the railcar. The hand wheel is attached through gearing to a rotatable axle which in turn is attached to a chain running down the side of the railcar. The gearing provides mechanical advantage allowing a person to operate the hand wheel. The chain may be directly connected, or via a rod, to a bell crank or shive wheel which in turn connects to a chain and top rod that runs under the undercarriage of the railcar, and which ultimately links to the brake rigging. Turning of the hand wheel turns the gear to gather up the chain around the axle, pulling the chain in tension and pivoting the bell crank, which in turn tensions the chain and top rod under the undercarriage of the railcar to operate the brake rigging, and thereby apply the brakes. Sufficient tension will prevent the wheels from turning. Turning the hand wheel in the opposite direction will release the brakes. Other forms of handbrakes include a hand lever that is operated manually to apply tension to the chain or rod that operates the brakes in a similar manner as described above.
Since a handbrake is specific to a single railcar, it is not uncommon for inspectors to overlook an individual railcar when checking to ensure that the handbrakes are released. Thus the railcar may be moved with the handbrakes applied.
Presently, there is no reliable system for monitoring the status of a handbrake and for indicating movement of the railcar with the handbrakes applied. One common type of device, as disclosed in U.S. Pat. No. 3,854,417, provides a visual signal, such as an indicator flag, which extends on the railcar when the handbrake is on. However, an inspector must be sufficiently close to see the signal, and it is unlikely to be seen by the train crew when the car is part of a long train. Another device, disclosed in U.S. Pat. No. 4,296,707, provides a whistle sound when the handbrake is on and air is applied to the air brake system. This requires that someone be sufficiently close to hear the whistle. Accordingly, improved monitoring devices are desirable.